JEE Main 2026 — Jan 28, Shift 2 — Physics solution

JEE Main2026Jan 28, Shift 2Physics

Two tuning forks A and B are sounded together giving rise to 8 beats in 2 s. When fork A is loaded with wax, the beat frequency is reduced to 4 beats in 2 s. If the original frequency of tuning fork B is 380 Hz, then the original frequency of tuning fork A is ______ Hz.

Your answer

Solution

Initial beat frequency $= \frac{8}{2} = 4$ Hz, so $∣ f_{A} - 380∣ = 4 \Rightarrow f_{A} = 384$ or $376$ Hz.

Loading wax decreases fork A's frequency. New beat frequency $= 2$ Hz.

If $f_{A} = 376$ , the loaded frequency falls further below 380, increasing the beat — inconsistent with 2 Hz.

If $f_{A} = 384$ , loading drops it toward 380, reducing the beat to 2 Hz — consistent. So $f_{A} = 384$ Hz.

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